Trim mowers, also sometimes referred to as utility mowers, may be used to mow the smaller and/or enclosed rough and fringe areas on golf courses. These areas may be too small or confined for larger mowing machines such as fairway mowers. Trim mowers may include three cutting units powered by and attached to a traction vehicle. For example, two front cutting units may be positioned forward of the vehicle's front pair of wheels, and a rear cutting unit may be between the front wheels and a single rear wheel used for steering. The rear cutting unit may cut a swath between the two front cutting units that overlaps the swaths cut by the two front cutting units.
Trim mowers have a tendency to “crab” when operated on side slopes that have relatively steep inclines or undulations that are common on many golf courses. Crabbing refers to the rear wheel tracking or sliding downhill from the centerline of the trim mower. Crabbing may cause the trim mower to leave uncut strips of grass. This occurs when the rear cutting unit tracks or slides downhill so much that it no longer can overlap the two front cutting units.
To prevent or minimize uncut strips, trim mowers may be designed with additional overlap between the front and rear cutting units. However, greater overlap also can reduce a trim mower's cutting width, resulting in lower productivity of the trim mower in flatter areas. A trim mower is needed having high versatility, and that will prevent or minimize uncut strips without sacrificing productivity.
When trim mowers are used to cut grass at or near the edge of a golf course hazard such as a sand trap or bunker, or other golf course feature, the machine's weight may cause the bunker wall to collapse, especially in sandy soil conditions. Additionally, a trim mower weighing 1000 pounds or more may slide into a sand trap or bunker, get stuck, become high centered, or tip over. A trim mower is needed that will reduce the risk of damage to golf course features such as sand traps or bunkers. A trim mower is needed that will minimize the risk of sliding into a sand trap or bunker, getting stuck, etc.
Efforts have been made to design and make trim mowers that solve one or more of these problems. For example, U.S. Pat. Nos. 6,032,441 and 6,351,929 relate to a triplex trim mower with a pair of laterally adjustable cutting units. The cutting units are supported by a lateral carrier frame which is slidably engaged to a lateral support frame. A hydraulic cylinder permits the carrier frame to be laterally displaced with respect to the vehicle frame so that a cutting unit can to reach the edge of a bunker or sand trap while the vehicle maintains a distance from that feature. When trimming around an obstacle on a slope with the cutting units shifted to the downhill side, the trim mower may become unstable. The instability may result from all cutting units being shifted by a single carrier. The carrier supports its own weight along with the cutting units, cylinders and lift arms. When the single carrier shifts the cutting units to a downhill side, the center of gravity of the mower is moved into a less favorable position that can cause the mower to tip over. If the cutting units are shifted to one side of the machine using the single carrier frame, the opposite side wheel and tire may roll on uncut turf, resulting in poor cut quality and an unsightly cut pattern. Additionally, the hydraulic hoses used to shift the cutting units may be subject to increased wear due to additional flexing and possible rubbing, resulting in leakage of hydraulic fluid onto the turf, and causing damage to the golf course and expensive repairs.
A trim mower is needed that is more stable, especially on steep slopes. A trim mower is needed that will not have a shifting center of gravity if one or more cutting units are extended outwardly. A trim mower is needed that will not cause the uphill tire to roll on uncut turf. A trim mower is needed that will have a better cut quality and cut pattern. A trim mower is needed that will minimize wear of hydraulic system hoses and reduce the risk of leakage of hydraulic fluid.
Other mowers have been proposed with cutting units that can move laterally. For example, U.S. Pat. No. 2,882,978 relates to a selectably slidable, laterally offset mower for trimming beneath overhanging obstacles such as low tree branches. U.S. Pat. No. 4,873,818 relates to a similar mower that provides increased offset capability. U.S. Pat. Nos. 4,893,456 and 5,483,789 relate to single cutting decks that can be laterally displaced from a conventional centered position to a laterally extended position. These devices are not well suited and have not been adapted for use on trim mowers that are used to cut rough and fringe areas on a golf course.
A trim mower is needed that includes a cutting unit that can reach and mow grass in small or enclosed areas of golf courses, especially around the edges of hazards such as sand traps and bunkers, but that will not sacrifice productivity when mowing other areas. A trim mower is needed having increased cutting width without sacrificing necessary overlap between front and rear cutting units. A trim mower is needed that has good stability when a cutting unit is moved laterally. A trim mower is needed that can reduce the risk of damage to the edges of sand traps and bunkers. A trim mower is needed having these features and advantages, and that can also mow at reduced widths on slopes to maximize the overlap and minimize uncut strips of turf.